188 ANNUAL OF SCIENTIFIC DISCOVERY. 



placed in the bath of hyposulphite of soia, composed of one part of 

 that salt to six of water, and completed in the usual manner. When 

 properly prepared, these photographs have all the air of fine mezzo- 



tmto engravings. 



May all? s Improvements in Crayon Daguerreotypes. The London 

 Athenseum gives a description of a beautiful recent invention of Mr. 

 Mayall, of London, by which he is enabled to produce an effect of ar- 

 rangement similar to that which the crayon painter imparts to his por- 

 traits. By its means a more truthful gradation is obtained, and the 

 force in the features of the face is freed from that exaggeration 

 hitherto inseparable from the process. The result is, a far more 

 agreeable version of the human face than has been hitherto obtained 

 by this instrument. Some specimens which have come under our no- 

 tice are much distinguished also for the beauty of their execution, 

 the tint being harmonious and neutral, the various textures of flesh, 

 hair, drapery, &c., discriminated with a painter's taste, and an entire 

 absence of a certain commonness of aspect which has tended hitherto 

 to disparage this art. The mechanical arrangement of this invention 

 consists, we are informed, of a slowly revolving disc, arranged on a 

 support somewhat like a fire-screen, and having a central opening in 

 the form of a large star. This disc is carried between the forks of a 

 framepiece, the stem of which is adjustable as to height in the pedes- 

 tal. To keep the disc in motion, an arrangement of clockwork is at- 

 tached to the framing, the actuating spring being contained in a 

 box, driving a spur-wheel in gear with a pinion on the spindle of the 

 fly. The screw for setting the disc up or down is at a certain point. 

 This apparatus is interposed between the object, or sitter, and the 

 camera ; and the central portion of the star is made large enough to 

 admit the rays from that part of the object which is to be shown in 

 strong light, whilst the rays from those parts which are to be gradual- 

 ly shaded off to a dark background are partially intercepted by the 

 points of the star. In this way the intensity of the light is gradually 

 destroyed, and the softened-off " crayon " effect is produced. The 

 apparatus is applicable to every description of camera, and by 

 placing it nearer to or further from the lens, any portions of the 

 image may be so softened off. 



The following improvement in the method of taking daguerreotypes 

 has been invented by James Brown, of New York. The apparatus 

 employed is used in conjunction with the camera, and consists of an 

 ornamental diaphragm placed in front with a suitable opening to take 

 the picture of the intended object. The front of the diaphragm may 

 be ornamented in any way by work in relief, or by drawing, painting, 

 or otherwise, so as to form on the daguerreotype an ornamental back- 

 ground. The diaphragm is made adjustable at different heights and 

 inclinations by being fixed in a swinging frame hung on pivots in a 

 standing frame, and having grooves to receive the sides of the 

 diaphragm. 



Portraits from Daguerreotypes. A plan has been devised by Mr. 

 Ransom, of New York, for painting portraits from daguerreotypes 



